Hi Pontus, it is not easy to remove a file association in Windows 10,
Open Windows File Explorer
On the view Ribbon (tab) check the box marked 'File Name Extensions'
Close File Explorer
Right click your Desktop and choose New - Text File
Change the file extension on that new file from .txt to .exe
Confirm the change
Right click a .package file, choose open with - Choose another App
Check the box marked 'Always use this app to open .package files' - IMPORTANT!
Scroll to the bottom and click 'More Apps'
Again scroll to the bottom and choose 'Find another app on this PC'
Navigate to the dummy file exe on your Desktop and click OK
The .package file will not open
Delete the dummy exe file on your Desktop and restart your PC
The file association will then be broken and it will be back to None!